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Modulating crack propagation in a multilayer stack with a super-layer

Quantitative characterization of interface adhesion and fracture properties of thin film materials is of fundamental and technological interests in modern technologies. Sandwich beam specimens used in fracture mechanics techniques, such as four-point bending and double-cantilever beam have been widely adopted, including the semiconductor industry.

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Engineer position at Intel (Hillsboro,OR)

 Intel has a potential opening for an entry-level Engineering position in the area of Thermal Mechanics.  If you would like more information on this position please contact me at li.han@intel.com with current resume. 

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Stiffening of organosilicate glasses by organic cross-linking

Atomistic simulations show that organosilicates, used as low-permittivity dielectric materials in advanced integrated circuits, can be made substantially stiffer than amorphous silica, while maintaining a lower mass density. The enhanced stiffness is achieved by incorporating organic cross-links to replace bridging oxygen atoms in the silica network. To elucidate the mechanism responsible for the enhanced stiffness, the conformational changes in the network upon hydrostatic and shear loading are examined.

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New methods of analyzing indentation experiments on very thin films

Abstract - Indentation experiments on very thin films are analyzed by employing a rigorous solution to model elastic substrate effects. Two cases are discussed: elastic indentations where film and substrate are anisotropic, and elasto-plastic indentations where significant material pile-up occurs. We demonstrate that the elastic modulus of a thin film can be accurately measured in both cases, even if there is significant elastic mismatch between film and substrate. 

This manuscript has been accepted for publication in Journal of Materials Research.  

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Water diffusion and fracture behavior in nano-porous low-k dielectric film stacks

Among various low-dielectric constant low-k materials under development, organosilicate glassesOSGs containing nanometer-size pores are leading candidates for use as intrametal dielectrics infuture microelectronics technologies. In this paper, we investigate the direct impact of waterdiffusion on the fracture behavior of film stacks that contain porous OSG coatings.

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Determining the elastic modulus and hardness of an ultra-thin film on a substrate using nanoindentation

Abstract – A data analysis procedure has been developed to estimate the contact area in an elasto-plastic indentation of a thin film bonded to a substrate. The procedure can be used to derive the elastic modulus and hardness of the film from the indentation load, displacement, and contact stiffness data at indentation depths that are a significant fraction of the film thickness. The analysis is based on Yu’s elastic solution for the contact of a rigid conical punch on a layered half-space and uses an approach similar to the Oliver-Pharr method for bulk materials.

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The effect of porosity on the stiffness and fracture energy of brittle organosilicates

Integrating porous low-permittivity dielectrics into Cu metallization is one of the strategies to reduce power consumption, signal propagation delays, and crosstalk between interconnects for the next generation of integrated circuits. However, the porosity and pore structure of these low-k dielectric materials also strongly affects other important material properties besides their dielectric constant.

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